Autogenic Microbial Genesis of Middle Miocene Palustrine Ooids; Nullarbor Plain, Australia
Bibliographic record
Abstract
Abstract: Miocene palustrine ooids located in the Nullarbor Plain, southern Australia, illustrate the importance of microbes and soil processes in the formation of these spherically laminated grains in pedogenic settings. These particles are composed of dense minimicrite and include a wide assortment of microbially produced structures. Such biogenicity includes interpreted extracellular polymers (EPS), algal filaments, palygorskite and sepiolite nano-fiber mats, bacterial spores, and meniscate fabrics. Ooid nuclei are peloids that are interpreted to have formed via microbial binding of lacustrine sediment in a subsequent palustrine environment, both at the surface and inside underlying karst cavities. The peloids are encapsulated in multigenerational micrite laminations that form the spherical cortex. Individual cortical laminae are made up of degraded minimicrite crystals and complex encrusting mats of palygorskite and sepiolite nano-fibers. Cortex generation is interpreted to have been an annual process involving alternating soil hydration states. In this conceptual model, during the wet season, ooids were covered in bacterial mucus that bound ions from solution and produced hydrated Mg-Si gels that evenly surrounded the entire ooid. Gel dehydration during the following dry season resulted in precipitation of fibrous palygorskite and sepiolite. Succeeding seasonal variations in moisture produced numerous laminae that ultimately resulted in a multigenerational ooid cortex. This annual microbial process provides a new mechanism involving an autogenic formation of ooids that may be applied to a wide variety of pedogenic sediments. Unlike the more common marine ooids that require constant movement to achieve cortical precipitation, the process of grainification, combined with microbially mediated mineral precipitation under different soil hydration states, results in the in-place formation of terrestrial ooids.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".